Cogging torque is a condition present in most permanent magnet electric machines, for example electrical motors and generators. When unenergized, the electrical machine seeks a rotational position that results in the lowest magnetic circuit reluctance (or the highest permeance). This condition may be perceived as intermittent resistance to rotation of the electrical machine. The net cogging torque as the electrical machine rotates is zero, as the cogging torque alternately “resists” and “encourages” rotation of the electrical machine. However, because the momentary cogging torque at most rotational positions of the electrical machine is non-zero, the cogging torque causes noise and vibration within the electrical machine. This can potentially lead to wear on and/or premature failure of electrical and/or mechanical components. Additionally, it can cause vibration within systems driven by and/or driving the electrical machine, resulting in additional noise, wear, and/or failure.
Because of these and other undesirable consequences of cogging torque, many prior approaches for reducing and/or minimizing cogging torque have been attempted. However, it remains desirable to provide improved systems and methods for reducing and/or minimizing cogging torque in electrical machines and/or providing electrical machines having back EMF waveforms that more closely approximate an ideal sinusoid, particularly in transverse flux machines and/or commutated flux machines.